Inspecting abrasive grinding wheels



Nov. 2, 1965 w. w. WELLBORN 3,214,965

INSPECTING ABRASIVE GRINDING WHEELS Filed May 31, 1962 2 Sheets-Sheet 1 efcaepae FIG. 2

INVENTOR. WILLIAM W WELL BORN ATTORNEYS Nov. 2, 1965 w, w. w o 3,214,965

INSPEC'IING ABRASIVE GRINDING WHEELS Filed May 51, 1962 2 Sheets-Sheet 2 FIG. 6

FORCE ORCE FIG. 7

FORCE FORCE F ,6 9

FIG. 6 NVENTOR.

WILLIAM W ELL Bonn! ATTORNE Y5 United States Patent 3,214,965 INSPECTING ABRASIVE GRINDING WHEELS William W. Wellborn, Milford, Mich, assignor to Abrasive Dressing Tool Company, Detroit, Mich, a corporation of Michigan Filed May 31, 1962, Ser. No. 199,104 9 Claims. (CI. 73-78) This invention relates to inspecting abrasive grinding wheels and particularly to inspecting abrasive grinding wheels to determine density, bond strength, grain size, and grain size distribution.

In abrasive grinding Wheels which include abrasive grains such as silicon carbide, aluminum oxide particles and the like, it is desirable to know as closely as possible the various properties of the abrasive grinding wheels, such as density, bond strength, grain size, and grain size distribution.

It is an object of this invention to provide a method for readily inspecting abrasive grinding wheels to determine these properties.

Basically, the method comprises rotating a grinding wheel about its axis, bringing a cutting member into contact with the periphery of the grinding wheel and causing it to traverse the width of the grinding Wheel, and measuring and recording the variations in forces on the cutting member as the cutting member traverses the periphery of the grinding wheel. By studying the variation in the forces, the density and bond strength of the grinding wheel in various portions thereof may be readily determined. In addition, by magnifying the forces on the cutting member, the grain size and distribution can be determined by application of relatively simple formulas.

In the drawings:

FIG. 1 is a fragmentary elevation of an apparatus embodying the invention.

FIG. 2 is an end view of a portion of the apparatus shown in FIG. 1.

FIG. 3 is a perspective diagrammatic view showing the inspection of an abrasive grinding wheel.

FIG. 4 is a fragmentary side elevation, on an enlarged scale, of the method as shown in FIG. 3.

FIG. 5 is a fragmentary sectional view, on an enlarged scale, taken along the line 5-5 in FIG. 2.

FIGS. 6-9 are charts representing various results that may be obtained by utilizing the method.

Referring to the drawings, the apparatus for performing the method comprises a device by which the grinding wheel G which is to be inspected is supported and rotated about its axis. In addition, a support 10 holds a cutting member or tool 11 having a cutting tip 12, such as a diamond, which is adapted to be brought into position adjacent the periphery of the wheel G and moved in a direction parallel to the axis of the wheel to traverse the width of the wheel in a manner shown in FIG. 3. Cutting member 11 is mounted on a dynamometer support 13 which is adapted to measure the forces on the cutting member 11.

As shown in FIG. 5, the dynamometer comprises a tube 14 On which cutting tool 11 is directly mounted. Annular flanges 15, 16 extend radially outwardly into contact with a cylindrical Wall 17 in support 10. By locating a strain gage 18 on tube 14, axial forces on cutting tool 11 can be recorded. By locating strain gages 19, 20

Patented Nov. 2, 1965 on flanges 15, 16, the lateral and tangential forces, respectively, on the cutting tool 11 can be recorded.

By use of the device shown in FIGS. 1, 2 and S, the forces on the cutting member may be recorded on recorder 10 as it traverses the width of the grinding wheel. Thus, as shown in FIGS. 3 and 4, the axial force A on the cutting member, the lateral force L and the tangential force T can all be recorded. The forces can be transferred and recorded on a chart which is movable at a uniform lineal speed so that various curves, such as shown in FIGS. 6-9, can be obtained. As shown in FIGS. 6 and 7, fluctuations in force on the cutting member may vary, depending upon the density and bond strength across the width of the wheel. If a concave type of curve, such as shown in FIG. 6 is obtained, a low density or bond strength at the center of the surface is indicated. A convex curve, such as shown in FIG. 7 indicates a high density or bond strength. The variations in force in traversing the width of the grinding wheel indicate the areas of varying density and bond strength. By comparing the average magnitude of the curves with a standard, the overall density and bond strength of a wheel can be determined with respect to the standard.

If the time units are shortened or the wheel caused' to travel at a reduced speed, magnified recordings of the force are obtained, as shown in FIGS. 8 and 9. These clearly indicate the grain size and grain size distribution or thickness of bond between grains.

Simple formulas can be used to determine the grain size and grain size distribution. Thus, in order to determine grain size, the relation used is:

Where:

d =the average diameter of dispersed grain.

N =the number of noncontiguous grains intersected by a line of unit length. N =the number of noncontiguous grains per unit area.

may be used.

Where:

P=the average distance between grains.

F=the volume fraction of the dispersed phase, that is, the ratio of the volume of the grains to the total volume of the wheel.

What I claim is:

1. The method of inspecting abrasive grinding wheels which comprises rotating an abrasive grinding wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the periphery of the abrasive grinding wheel while it is rotating,

causing said cutting member to traverse the periphery of the wheel in a direction generally parallel to the axis of the wheel,

and measuring the forces On the cutting member as it traverses the periphery of the rotating abrasive grinding wheel.

2. The method of inspecting abrasive grinding wheels which comprises rotating an abrasive grinding Wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the periphery of the abrasive grinding wheel while it is rotating,

causing said cutting member to traverse the periphery of the Wheel in a direction generally parallel to the axis of the wheel,

and measuring the forces on the cutting member in a direction parallel to the radial axis of the cutting member in a direction parallel to the axis of the wheel and in a direction tangential to the periphery of the wheel and at a right angle to the axis of the cutting member.

3. The method of inspecting abrasive grinding wheels which comprises rotating an abrasive grinding wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the periphery of the abrasive grinding wheel while it is rotating,

causing said cutting member to traverse the periphery of the Wheel in a direction generally parallel to the axis of the wheel,

measuring the forces on the cutting member as it traverses the periphery of the rotating abrasive grinding Wheel,

and recording the force per unit time, thereby obtaining a record of the variation in the force as the cutting member traverses the width of the abrasive grinding wheel.

4. The method of inspecting abrasive grinding wheels which comprises rotating an abrasive grinding wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the periphery of the abrasive grinding wheel While it is rotating,

causing 'said cutting member to traverse the periphery of the wheel in a direction generally parallel to the axis of the Wheel,

measuring the forces on the cutting member in a direction parallel to the, radial axis of the cutting member in a direction parallel to the axis of the Wheel and in a direction tangential to the periphery of the wheel and at a right angle to the axis of the cutting member,

and recording the force per unit time, thereby obtaining a record of the variation in the force as the cutting member traverses the width of the abrasive grinding Wheel.

5. The method of inspecting abrasive grinding Wheels which comprises rotating an abrasive grinding wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the periphery of the abrasive grinding wheel while it is rotating,

causing said cutting member to traverse the periphery of the wheel in a direction generally parallel to the axis of the wheel,

measuring the forces on the cutting member as it .traverses the periphery of the rotating abrasive grinding wheel,

and comparing the variations in the forces on the cutting tool with a standard to determine the variation in density and bond strength of the grinding wheel.

6. The method of inspecting abrasive grinding wheels which comprises rotating an abrasive grinding wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the pc- 5 riphery of the abrasive grinding wheel while it is rotating,

causing said cutting member to traverse the periphery of the wheel in a direction generally parallel to the axis of the wheel,

measuring the forces on the cutting member as it traverses the periphery of the rotating abrasive grinding wheel,

magnifying the forces on the cutting member per unit time such that fluctuations in the forces indicate the number of grains encountered by the cutting member, and comparing the fluctuations with a standard to thereby determine grain size and distribution. 7. The method of inspecting abrasive grinding wheels which comprises rotating an abrasive grinding wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the periphery of the abrasive grinding wheel while it is rotating, causing said cutting member to traverse the periphery of the wheel in a direction generally parallel to the axis of the wheel, measuring the forces on the cutting member as it traverses the periphery of the rotating abrasive grinding Wheel, and magnifying the forces on the cutting member to determine grain size and grain size distribution and utilizing the relationship of where 0! equals the average diameter of dispersed grains,

N equals the number of noncontiguous grains intersected by a line of unit length and may be taken as the number of force intercepts per revolution of the Wheel,

and N equals the number of noncontiguous grains per unit area and may be obtained by dividing the total number of intercepts in ten revolutions by the product of the total cross feed in inches, multiplied by the circumference of the wheel in inches.

8. The method of inspecting abrasive grinding wheels which comprises rotating an abrasive grinding wheel about its axis through a plurality of revolutions,

bringing a cutting member into contact with the pcriphery of the abrasive grinding wheel while it is rotating,

causing said cutting member to traverse the periphery of the wheel in a direction generally parallel to the axis of the wheel,

measuring the forces on the cutting member as it traverses the periphery of the rotating abrasive grinding wheel,

and determining the average thickness of the bond between grains of the abrasive by the relationship lminus F where P equals the average distance between grains and F equals the volume fraction of the dispersed phase, that is, the ratio of the volume of the grains to the total volume of the wheels.

9. Apparatus for determining the properties of an abrasive grinding wheel comprising,

means for rotating said grinding wheel about its axis of rotation,

a grinding wheel cutting member mounted adjacent said wheel adapted to be moved into contact with said wheel,

means for traversing said cutting member in a direction parallel to the axis of said Wheel,

means cooperating with and responsive to forces developed on said cutting member,

and means for indicating said forces as a measure of said properties.

References Cited by the Examiner UNITED STATES PATENTS 1,534,014 4/25 Gillett 739X 1,534,015 4/25 Swenson 737 6 OTHER REFERENCES Article entitled, Dynamic Wheel Hardness Testing; by T. W. Black; from The Tool and Manufacturing Engineer, October 1961, pages 83-86.

Article entitled, A Two Component Lathe Dynamometer; by B. L. Ten Horn et 211.; from Microtenic, vol. XI, No. 2, pages 59-66.

RICHARD C. QUEISSER, Primary Examiner.

1,637,676 8/27 Von Bohuszewicz et a1. 7378 X 10 JOSEPH P. STRIZAK, Examiner. 

1. THE METHOD OF INSPECTING ABRASIVE GRINDING WHEELS WHICH COMPRISES ROTATING AN ABRASIVE GRIDNING WHEEL ABOUT ITS AXIS THROUGH A PLURALITY OF REVOLUTIONS, BRINGING A CUTTING MEMBER INTO CONTACT WITH THE PERIPHERY OF THE ABRASIVE GRINDING WHEEL WHILE IT IS ROTATING, CAUSING SAID CUTTING MEMBER TO TRAVERSE THE PERIPHERY 